wrote:
Jim Backus wrote:
On Mon, 15 Oct 2007 15:02:15 UTC, Phil Gardner wrote:

HI
Just bought 4X 2700mHa Ni-MH AA battery's my old charger is not up to
charging these in a reasonable time C/10 so im looking to build my own
charger.

I have a 1.5 amp power supply what I need is a variable current
circuit add-on- about 150-800 mA but cant find anything Simple! as in
DIY simple.

Any thoughts, suggestions?
LM317 voltage regulator IC set up for constant current.

Googling on "LM317 constant current" produced this:

http://users.pandora.be/davshomepage/current-source.htm

remember to mount the regulator on a heatsink - a square of 1/8 inch
aluminium a couple of inches square should do the job

... but it won't do nearly such a good job (as in treating the cells
well so they last well) as a proper NiCd/NiMh battery charging chip.

You can buy the chips or beg a couple free off the manufacturer as I
did, problem is I can't rememeber the manufacturer's name now.

But a fast charger only costs a few quid.

You canhave my old one f you like. Ex model car racing charger. Does 4-8
cells at about 3A fast, dropping back to trickle when the delta peak is
detected. Runs off 12v or the mains. Can';t sell em for love nor money.